Search results

So you measured from pin 2 of J171 to pin 1 of Q801, which is the pin closest to the edge of the power supply PCB? I just want to make sure because you made the statement “Base is not in the middle”, and I never said anything about it being in the middle. And if you measured this with J171...

Measure for DC volts between J171 pin 2 and the base of transistor Q801. The base pin is the first one, the one closest to the edge of the power supply PCB.

600mV is very not right for pin 3 after startup. Yes, reference to pin 2 for ground is correct. Did you get that measurement with J171 connected or disconnected from the motherboard?

Too many posts. I can’t keep up with the blasts. Please let’s take things one step at a time.

Think about this…how can it be the heads, or only the heads? You connected a source to an input and got nothing at the output. No heads involved there. So logically the issue is further upstream. Yes the power mute circuit mutes all audio at all outputs for a couple seconds +/- at power...

Turn on the 34B. Give it a few seconds, and then measure for DC volts at pin 3 of J171. What do you get?

You’ve got your hands full and I’m not sure if I’m going to be able to help. Again if it is global then it has to be something high up in the chain. I would verify power is actually getting to the opamps…like check for DC volts at pin 4 or pin 8 of any of the 4558 or 4559 opamps. The other...

I think they’re accessed via a removable panel on the bottom of the deck…looking at the service manual (which is available for free on the internet, and if you don’t have a copy you should get it and study it, because I’m going to steer you toward that every time…) it looks like you remove the...

Post some pics of the headblock assemblies and heads if you want some feedback on condition and completeness.

If you have all the connectors for the head cabling at both ends, and enough cable length, and you have good soldering skills, sure you can desolder the wire tails from the head cable box assembly and solder the other terminated cable to the head box connectors. Just follow the methodology and...

Bad relay? Did you re-seat the amp cards? Does the problem follow the swap or no? Thoroughly clean the heads with the right supplies?

Cool. Got the complete servo setup on the C. Outage complete head lock assemblies? I see cut cabling on one of the head cable boxes. A harrowing rescue. Cool you got the transport remote as well. How many signal electronics modules did you rescue? I think I only see one in the car...

Hi. I’m a little confused. The thread title suggests you are trying to decide between a computer audio interface or an analog mixer, but your first post suggests you are only weighing computer audio interfaces. If you are only looking for feedback about computer audio interfaces may I suggest...

The R8 is a great little open reel 8 track, but the transport on the 38 is more robust. There are lots of machines that are more robust than the 38, but it’s a solid machine as far as the design, it’s pretty reliable, and there are LOTS of them out there, so it’s a good machine for user...

Right. Put the fuse in. F501 also passes power for the +6V rail. No fuse, no power.

Unplugging J171 isolates the power supply…disconnects power from the rest of the machine. You are measuring 6mV on the +6V power rail. One of the things that rail powers is the VU meter lamps.

The fuse is not slow blow according to the service manual for USA versions. Local auto parts stores are also a good source for those types of fuses. Yes, that power supply for the power mute circuit and control signals and functionality do propagate over J171. And thanks for the...

Hey so first off, yes, there are multiple 0V references, but each is specific to a power rail. Each is the 0V reference for a specific rail or rails and you’ll get false readings if you use the reference for one rail as the reference for a rail that’s not relevant. So, here are the power rails...

Ahhh okay. So, no shame…sometimes ‘1’ is printed on the PCB, or sometimes you can find a ‘1’ on the connector housing noting pin 1.

That all makes sense FWIW. And yes…I think it’s very beneficial to have a spare machine. I even called it one of the most underrated “accessories” to a tape machine at one point. I have gobs of spares for my Ampex machine…a complete spare transport and electronics for my 3M halftrack…a, for...